Optical switches are used in optical systems to switch a light beam between one or more input fibers and one or more output fibers. For example, optical switches are used in optical communication systems to connect and disconnect transmission paths to route light beams modulated with information, provide network protection, provide cross connection, and for add/drop applications. Optical switches also can be used to pulse a light source, e.g., a laser, or perform other functions with modulated or unmodulated light beams.
One type of optical switch is a 1×2 optical switch, which provides optical switching between one input port and two output ports. It is known that 1×2 optical switches using refractive optics are very reliable, have small insertion loss, and are easy to manufacture. The 1×2 optical switch has been used widely in the telecommunications industry, such as for protection switching, tag switching, etc. The 1×2 optical switch also has been used to build larger dimension switches, such as 1×4 and 1×8 optical switches. In some cases, the application needs to integrate multiple 1×2 optical switches together to reduce power consumption and/or physical space used. Another type of optical switch is the 2×2 optical switch, which provides optical switching between two input ports and two output ports. Unlike most 1×2 switches, which have low switch cycles, most 2×2 switches that are used for cross-connections or add/drop applications require much higher durability and reliability.
There are many technologies used to implement these switches, such as mechanical, electro-optic, thermo-optic, acousto-optic, magneto-optic and semiconductor technologies. Each switching technology has advantages and disadvantages. For example, mechanical switches are the most widely used routing components and provide very low insertion loss and cross-talk characteristics. However, the switching times of mechanical switches are limited to the millisecond range and the devices themselves are bulky. Moreover, if motor-driven parts are used to operate the switch, the switch will have a limited operative lifetime and may suffer from reliability issues.